High performance image capture reader with low resolution image sensor

Abstract

A reader for and method of electro-optically reading symbols aim a front of a handheld housing at a symbol during reading. A solid-state, low resolution image sensor having a linear array of pixels is arranged in the housing and has less than 2000 pixels in number. The pixels sense return light returning along an optical path away from the symbol that is located in an extended range of working distances relative to the front of the housing. An imaging lens is positioned deep in the housing at an increased spacing of at least one inch as measured along the optical path away from the front of the housing, for capturing the return light over a reduced scan angle that is less than 40 degrees, and for projecting the captured light onto the sensor. A controller processes the return light sensed by the imager into data relating to the symbol.

1. A reader for electro-optically reading symbols, comprising:
 a handheld housing having a front that faces a symbol during reading; 
 a solid-state, low resolution image sensor having a linear array of pixels arranged in the housing along a scan direction and being less than 2000 in number, for sensing return light returning along an optical path away from the symbol that is located in a range of working distances relative to the front of the housing; 
 an imaging lens positioned in the housing at a spacing of at least one inch as measured along the optical path away from the front of the housing, for capturing the return light over a reduced scan angle that is less than 40 degrees, and for projecting the captured light onto the sensor; and 
 a controller for processing the return light sensed by the sensor into data relating to the symbol. 
 
     
     
       2. The reader of  claim 1 , and a light-transmissive recessed window on the housing and positioned in the housing along the optical path away from the front of the housing. 
     
     
       3. The reader of  claim 1 , wherein the image sensor is a one-dimensional charge coupled device (CCD) and has 1500 pixels in number. 
     
     
       4. The reader of  claim 1 , wherein the increased spacing of the imaging lens is greater than 1.5 inches away from the front of the housing. 
     
     
       5. The reader of  claim 1 , wherein the imaging lens projects the pixels over a virtual scan line that extends over the scan direction entirely across the symbol located at about one-half inch away from the front of the housing in a near region of the range of working distances. 
     
     
       6. The reader of  claim 1 , wherein the imaging lens projects the pixels over a shortened virtual scan line that extends over the scan direction across the symbol located at about twenty-four inches away from the front of the housing in a far region of the range of working distances, and wherein the projected pixels have a size adequate to resolve the symbol in said far region. 
     
     
       7. The reader of  claim 6 , and an illuminating light assembly for illuminating the symbol in said far region with intense illumination light over the shortened virtual scan line. 
     
     
       8. The reader of  claim 1 , and an illuminating light assembly including a pair of illuminating light sources positioned deep in the housing at an increased spacing of at least two inches as measured along the optical path away from the front of the housing, for uniformly illuminating the symbol with illumination light. 
     
     
       9. The reader of  claim 8 , wherein the illuminating light assembly including a pair of illuminating lenses positioned in the housing forwardly of the imaging lens. 
     
     
       10. A method of electro-optically reading symbols, comprising the steps of:
 aiming a front of a handheld housing at a symbol during reading; 
 sensing return light returning along an optical path away from the symbol that is located in a range of working distances relative to the front of the housing with a solid-state, low resolution image sensor having a linear array of pixels arranged in the housing along a scan direction and being less than 2000 in number; 
 positioning an imaging lens in the housing at a spacing of at least one inch as measured along the optical path away from the front of the housing, and configuring the imaging lens to capture the return light over a reduced scan angle that is less than 40 degrees, and to project the captured light onto the sensor; and 
 processing the return light sensed by the sensor into data relating to the symbol. 
 
     
     
       11. The method of  claim 10 , and positioning a light-transmissive recessed window in the housing along the optical path away from the front of the housing. 
     
     
       12. The method of  claim 10 , and configuring the image sensor as a one-dimensional charge coupled device (CCD) with 1500 pixels in number. 
     
     
       13. The method of  claim 10 , wherein the step of positioning the imaging lens is performed by configuring the increased spacing of the imaging lens to be greater than 1.5 inches away from the front of the housing. 
     
     
       14. The method of  claim 10 , and configuring the imaging lens to project the pixels over a virtual scan line that extends over the scan direction entirely across the symbol located at about one-half inch away from the front of the housing in a near region of the range of working distances. 
     
     
       15. The method of  claim 10 , and configuring the imaging lens to project the pixels over a shortened virtual scan line that extends over the scan direction across the symbol located at about twenty-four inches away from the front of the housing in a far region of the range of working distances, and wherein the projected pixels have a size adequate to resolve the symbol in said far region. 
     
     
       16. The method of  claim 15 , and illuminating the symbol in said far region with intense illumination light over the shortened virtual scan line. 
     
     
       17. The method of  claim 10 , and uniformly illuminating the symbol with illumination light by positioning a pair of illuminating light sources deep in the housing at an increased spacing of at least two inches as measured along the optical path away from the front of the housing. 
     
     
       18. The method of  claim 17 , and positioning a pair of illuminating lenses in the housing forwardly of the imaging lens.